Aces High Bulletin Board
General Forums => The O' Club => Topic started by: Dichotomy on December 12, 2010, 04:56:27 PM
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http://msn.foxsports.com/video/shows/nfl-on-fox?vid=ca15cffb-3b66-49a0-84ca-20ed0a175567&from=msnhp>1=39002
holy wow :O glad nobody was hurt
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WOW!!
Wonder how deep that pile of snow is in the middle of the field?
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In the end... The Gints will have to wait a day to get their butts whooped by the best 63 year old QB that ever played.
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That is why I love the Superdome. Even with the force of Katrina the roof held up. Had a couple holes in it, but still held up.
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Can you imagine had that happened during a game... anyone under that would have been toast.
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It has happened before--back when they called it the HHH Humphrey Dome. It was a far more fragile "inflated" dome back them. Dumb mistake in an area where ice & snow can be on the ground from October to May.
I vividly remember May of 1982 when in Winona, MN the "mountain" of plowed snow & ice was still around the parking lot light poles in May.
It comes with the neighborhood.
ROX
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Can you imagine had that happened during a game... anyone under that would have been toast.
There are some photos out there from the inside. It didn't collapse, just deflated and is hanging down. The seats are all still well below it and while there is some snow on the field, it isn't that much.
I doubt there would have been any fatalities if it had been occupied unless people panicked.
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Engineering Fail.
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No doubt Grizz
ya think somebody, somewhere, is pooping in his or her pants right now?
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No doubt Grizz
ya think somebody, somewhere, is pooping in his or her pants right now?
What the heck happened? Excess snow simply caused it to collapse? I don't know the details but shouldn't it have been designed to withstand those snow loads? lol.
We're not talking a 100 year storm or anything here.
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even mother nature doesn't want Favre's streak to come to an end :lol :aok
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It has happened before--back when they called it the HHH Humphrey Dome. It was a far more fragile "inflated" dome back them. Dumb mistake in an area where ice & snow can be on the ground from October to May.
I vividly remember May of 1982 when in Winona, MN the "mountain" of plowed snow & ice was still around the parking lot light poles in May.
It comes with the neighborhood.
ROX
http://bleacherreport.com/articles/541322-metrodome-collapse-the-latest-news-on-giants-vs-vikings-game/entry/34167-minneapolis-metrodome-a-history-of-dome-collapses
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What the heck happened? Excess snow simply caused it to collapse? I don't know the details but shouldn't it have been designed to withstand those snow loads? lol.
We're not talking a 100 year storm or anything here.
Two of the panels tore and it deflated, as I understand it.
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What the heck happened? Excess snow simply caused it to collapse? I don't know the details but shouldn't it have been designed to withstand those snow loads? lol.
We're not talking a 100 year storm or anything here.
No clue as I haven't got any idea what that roof is constructed of. I just re watched the video and it appears that the fabric began tearing in the middle the it just cascaded from there. So my initial reaction is fatigue but that's a guess and I wouldn't hang my hat on it. I'll keep an eye out for any reports that come out. If you see something let me know.
Not exactly my discipline but there's very little that's not worth learning huh? I'm still looking at the data you forwarded as time allows. Those videos were fanfreakingtastic. If you ever need any AASHTO stuff let me know.
I'm starting to learn how to design wind turbine poles. EIA / TIA 222G. Totally different world from AASHTO ..
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There are some photos out there from the inside. It didn't collapse, just deflated and is hanging down. The seats are all still well below it and while there is some snow on the field, it isn't that much.
I doubt there would have been any fatalities if it had been occupied unless people panicked.
The roof collapsed, the weight of this latest snowfall caused it to do just that. That is a significant quantity of snow btw. We got hit with the same weather pattern today and I can understand why the roof collapsed.
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Until the factors that contributed to this are determined speculation, while intellectually interesting, is just that. Speculation.
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I cant imagine that roof was designed for any loading at all.
They should play outside anyways. Makes em better...Pats for instance.
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well someone who structurally engineered that Roof is going to have some explaining to do, wether systems failed to prevent the buildup on the Roof will have to be determined
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I cant imagine that roof was designed for any loading at all.
That would be professional suicide for any structural engineer. We don't know the factors that were involved but it will probably be released eventually and studied extensively. Grizz is much more well informed on this area of expertise than I am so any speculation at this point is only that. Speculation.
They just showed it again at halftime and it looks to me like the fabric failed and caused a catastrophic failure across the boards. What factors contributed to that are really difficult to ascertain at this point.
But again that's just speculation.
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It's simple. The weight of the wet snow exceeded the holding capacity of the roof and the heating space in between the two layers of fabric.
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It's simple. The weight of the wet snow exceeded the holding capacity of the roof and the heating space in between the two layers of fabric.
Yeah but that's ridiculous from a design standpoint. Either the fabric capacity was incorrect or the design snow loads were incorrect I would think.
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Grizz,
I read an article this morning that said they were cleaning the snow off Saturday evening but stopped for safety reasons.
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I wonder if it was designed to require constant snow removal?
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The fact that the dome is 27 years old wouldn't have anything to do with it would it?
:rolleyes:
Engineer flaw my back side...
Strip
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Strip, great minds think alike. :devil
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Don't know. I asked the PE I work with what he thought this morning. 'Too much snow' was the answer :lol But he said if he saw anything in his periodicals or email alerts he'd forward the information to me.
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The SR-71 was engineered quite some time ago. Still as amazing today as it was way back then.
I think the failure may have been in the tests conducted on the teflon material. There is some reason they used teflon.... could it have been a thought that snow would not stick to it? Nobody on the outside will ever know. We have no insight on why they chose the fabric that they did.
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...this isn't the first time that roof has collapsed due to excess snow...someone already provided a link that goes into detail about previous collapses
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The SR-71 was engineered quite some time ago. Still as amazing today as it was way back then.
I think the failure may have been in the tests conducted on the teflon material. There is some reason they used teflon.... could it have been a thought that snow would not stick to it? Nobody on the outside will ever know. We have no insight on why they chose the fabric that they did.
Your comparing a high performance aircraft engineering to structural engineering?
One with nearly an unlimited budget no less....not exactly apples to apples.
Strip
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The fact that the dome is 27 years old wouldn't have anything to do with it would it?
:rolleyes:
Engineer flaw my back side...
Strip
27 years isn't that old.
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Technology has changed dramatically in 27 years.
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For a dome it is...
Strip
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I'm thinking that hey had some kind of heat failure that prevented the Roof from melting acumalated snow buildup, After doing some reading i found this to be interesting, could of been a system malfuntion
The roof
The Metrodome roof.The Metrodome's roof is made of two layers of Teflon coated fiberglass fabric, and is an air-supported structure supported by positive air pressure. It requires 250,000 ft³/min (120 m³/s) of air to keep it inflated. It is reputed to be the largest application of Teflon on Earth, To maintain the differential air pressure, spectators usually enter and leave the seating and concourse areas through revolving doors, since the use of regular doors without an airlock would cause significant loss of air pressure. The double-walled construction allows warmed air to circulate beneath the top of the dome, melting accumulated snow.
A sophisticated environmental control center in the lower part of the stadium is manned to monitor weather and make adjustments in air distribution to maintain the roof.
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So, somebody forgot to turn the thermostat up? :)
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lol so you seen the keyword MANNED , after reading on that roof system it's a simple system really, I've seen similar designs on 1/2 acre sized greenhouses dual hvy gauge clear vinyl Air is used to inflate the roof and as the weather gets colder the heating fans kick in to keep the ice or snow off the greenhouse roof's ( metrodome is similar but on a much bigger scale) the key factor is the heated Air needed to remove and snow that builds up :aok i've designed enough homes and other buildings to know that snowloads are a very important factor in determing a roof system, pitch and materials to be used
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Can you imagine had that happened during a game... anyone under that would have been toast.
Possible, but unlikely, mind you a very severe weather event was in mid occurance and I'd imagine it would of been a signifigant hinderance and deterant to anyone intending to get to anywhere in the area, nevermind to a stadium for a football game. But that would be before taking into account the average darwin-IQ of your average NY Giants player and fan.
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Engineering Fail.
General Uneducated Public-Perception Fail...
Kinda-sorta an engineering fail, but I'm thinking along the lines here of crusifying the Value Engineers (who are far more accountants than engineers) while everyone is thinking of throwing up the pencil-protector wearing professionals... ...if the water and ice was comming up through the ground and into the stadium then it would be a civil engineering failure. The client-representing but standards, safety and building code-complying structural engineers might be the ones to blame here for proposing an inadequate alternative to your standard solid roof, but I'm leaning twords pointing the finger at the over-ruling grand-pumba having-the-final-say client-representing value engineers who probabley won the day (and largest share of their client's attention), and all without any responcibility or liability. Yup, I think I'm going to go with the value engineers winning that day here and the client/owner of the stadium being too fu!@ing cheap to pay for a traditional or more heartily constructed alternative.
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General Uneducated Public-Perception Fail...
Kinda-sorta an engineering fail, but I'm thinking along the lines here of crusifying the Value Engineers (who are far more accountants than engineers) while everyone is thinking of throwing up the pencil-protector wearing professionals... ...if the water and ice was comming up through the ground and into the stadium then it would be a civil engineering failure. The client-representing but standards, safety and building code-complying structural engineers might be the ones to blame here for proposing an inadequate alternative to your standard solid roof, but I'm leaning twords pointing the finger at the over-ruling grand-pumba having-the-final-say client-representing value engineers who probabley won the day (and largest share of their client's attention), and all without any responcibility or liability. Yup, I think I'm going to go with the value engineers winning that day here and the client/owner of the stadium being too fu!@ing cheap to pay for a traditional or more heartily constructed alternative.
I'm thinking along the lines of engineering fail. :aok
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That would be professional suicide for any structural engineer. We don't know the factors that were involved but it will probably be released eventually and studied extensively. Grizz is much more well informed on this area of expertise than I am so any speculation at this point is only that. Speculation.
They just showed it again at halftime and it looks to me like the fabric failed and caused a catastrophic failure across the boards. What factors contributed to that are really difficult to ascertain at this point.
But again that's just speculation.
The fabric failed because the dome collapsed. The collapsing dome funneled all the snow, ice and water to the lowest point via gravity. You'll note it did not signifigantly tear/rip/fail until it had collapsed and all the water on the dome was being forced down in a small and specific area of the entire dome. The fabric is semi-permiable to allow the hot air and moisture generated off a large crowd of people to disipate through it.
My best bet/guess at the cause of this collapse is in the video footage from the inside, showing an empty and dark stadium with all the grounds workers inside wearing very heavy clothing (meaing it must of been pretty cold in there). I think the stadium owner turned down the heat (or it was an unusally cold storm), either for some money saving or maintenance, and the fabric dome was designed to be heated, either independently or by the same air used to help push it up. With the lack of heat source, ice and snow began to build up on the roof. By the time the first indent was made and the first small leaks started (and water/snow/ice had nowhere to go) it was probabley too late to prevent it from snowballing.
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No disagreement here Babalonian and I'd have to agree on the surface with your assessment however as I'm not directly involved I've done as much research on the history of the stadium and the factors that have been released to the public as I can.
Stuff like this interests me and I try to read the reports when they come out to further my very general knowledge of structural engineering.
But it's nice to be able to bounce thoughts off of people who have similar interests and a more formalized education than I do.
Then I start learnin and stuff. And I like learnin. ;)
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I'm thinking along the lines of engineering fail. :aok
I'm thinking since it was engineered to meet the requirements specificied and detailed by the paying owner or his design team, it's the owner's or designer's fault. They should of specified a more expencive, durable and reliable alternative as I'm sure the structural engineers designed it to the specifications that they had to.
In a perfectly safe world the structural engineer has complete control and the final say in engineering X componenet on Y structure. In a prefect world... they would be but this isn't a perfect world, and the designers, investors and value engineers have a lot more say in things than any of the real engineers.
OK folks, time to play the "Grizz knows everything" game here. Lets say it is the fault of the structural engineers. How is it their fault in this instance? They might of not built the roof to the local and state building and safety codes and requirements, it might not of been able to handle the snow and ice.... oh wait, then how did they get issued a building permit by the local and state building and safety administrations? Well they must of not had one... well, wait, no, this was not built before the late 1800s, so it's impossible for them to of built it without all the proper permits and waivers... well that's a possibility, it was awarded a waiver by the state and local agencies, so since the state and locals said it was OK and met the bill, it must be their fault!... well wait, that still makes it so the structural engineering guys aren't at fault and did what they were supposed to and payed to do.
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OK folks, time to play the "Grizz knows everything" game here. Lets say it is the fault of the structural engineers. How is it their fault in this instance? They might of not built the roof to the local and state building and safety codes and requirements, it might not of been able to handle the snow and ice.... oh wait, then how did they get issued a building permit by the local and state building and safety administrations? Well they must of not had one... well, wait, no, this was not built before the late 1800s, so it's impossible for them to of built it without all the proper permits and waivers... well that's a possibility, it was awarded a waiver by the state and local agencies, so since the state and locals said it was OK and met the bill, it must be their fault!... well wait, that still makes it so the structural engineering guys aren't at fault and did what they were supposed to and payed to do.
:rofl :rofl :rofl
First of all, all I said was "engineering fail". That is such a broad based comment I don't know why you are epically ranting over this. I could have meant the engineering of the fabric, or the engineering of the heating system, or the engineering of the roof. I honestly have not even looked into it at all other than this thread and the general news articles. I'm sorry for inferring that the structural engineer might have been to blame. Are you a structural engineer? I'm not, but I will be in about 3 years after I graduate with my M.S. in Structural Engineering, and finish up my work requirements to get licensed in my state. Anytime you want to talk loads, codes, dynamics, structural reliability, concrete design, steel design, masonry design, wood design, seismic design, etc. Let me know. :aok
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I always want to talk that stuff :D
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First off they never should have designed a fabric roof in Minnesota where it is possible to get 17" snow loads in a 24 hour period. So yes, design fail, huge design fail, but that 30 years late.
Second, while I have no proof, after the first dome collapse when it snowed they'd get people up there to get the snow off. With the dome about to be phased out I suspect someone was cutting back on the upkeep money being spent. With a normal snowfall you can probably cut 25 people back to 10 or so and still get the job done. How many where sent up to clear it compared to the past, well I have no way of getting that information. Also was there delay before the crews were sent up? Was someone sleeping at the switch? Slow to move or to spend money?
Seems pretty obvious that they came down because they could see that it was deflating and hence was going to fail. Once you start deflating a fabric dome like that snow instead of blowing, sliding off will accumulate in the center accelerating the process of failure.
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I'm thinking since it was engineered to meet the requirements specificied and detailed by the paying owner or his design team, it's the owner's or designer's fault. They should of specified a more expencive, durable and reliable alternative as I'm sure the structural engineers designed it to the specifications that they had to.
Building code :)
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Based on latest code it probably should have been designed, assuming a cold roof, for 24psf flat snow load, 5psf rain on snow, round it up to 30psf...(not sure about the code 30 years ago)
30psf load with 20.5pcf density
30/20.5 = 1.46ft = 17.6 inches snow design. Assuming no unbalanced snow, (and proper drainage) which I don't know enough about a dome structure to know if you can make that assumption. So hell, after all safety factors, are taken into account from both snow loads and fabric loads I would think it would be able to take at least 40psf of load before failing, which would be 2 feet of snow. Not enough info though.
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Based on latest code it probably should have been designed, assuming a cold roof, for 24psf flat snow load, 5psf rain on snow, round it up to 30psf...(not sure about the code 30 years ago)
30psf load with 20.5pcf density
30/20.5 = 1.46ft = 17.6 inches snow design. Assuming no unbalanced snow, (and proper drainage) which I don't know enough about a dome structure to know if you can make that assumption. So hell, after all safety factors, are taken into account from both snow loads and fabric loads I would think it would be able to take at least 40psf of load before failing, which would be 2 feet of snow. Not enough info though.
As heavy of a snowfall as this was, it wouldn't have mattered. This snowstorm that hit us the day was as wet as can be. Domes have no place up here, down South or out West in the warmer climates, absolutely.
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I'm thinking since it was engineered to meet the requirements specificied and detailed by the paying owner or his design team, it's the owner's or designer's fault. They should of specified a more expencive, durable and reliable alternative as I'm sure the structural engineers designed it to the specifications that they had to.
Wrong. Any structural engineer that designs to the customer’s specifications and neglects the governing codes will not be an engineer very long. It is the responsibility of the engineer to protect the public even if that means the customer has to cancel the project because they are not willing to cover the cost. I don’t know all of the details related to this case so I will withhold my opinion, but I will say that the roof should have been designed according to the local and state building codes which would allow for a snowfall like that roof just experienced. If the engineer didn’t do that, they are very fortunate nobody was hurt and they deserve the lawsuit that is heading their way.
SunBat, P.E.
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As heavy of a snowfall as this was, it wouldn't have mattered. This snowstorm that hit us the day was as wet as can be. Domes have no place up here, down South or out West in the warmer climates, absolutely.
The design snow density for minneapolis is 20.5 pcf. Water is 62.4 pcf for comparison.
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As heavy of a snowfall as this was, it wouldn't have mattered. This snowstorm that hit us the day was as wet as can be. Domes have no place up here, down South or out West in the warmer climates, absolutely.
I know of domes in Red Dog, Alaska and Sahklin Island, Russia that had way more snow than that and never fell down. As a matter of fact, I used to work for the company that made those domes.
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As a matter of fact, here is the last dome I designed at that company before I left. This is as seen from Google Earth. It is in New Braunfels, TX.
(http://dasmuppets.com/public/Sunbatt/dome.jpg)
Here is one I dug up taken from the ground right after construction of the dome was complete...
(http://dasmuppets.com/public/Sunbatt/dome2.JPG)
EDIT: She was still on the ground and not permentantly mounted to the wall when Hurricane Ike came through and I had to design a tiedown system to keep her from flying away during the storm. It was rather nerve racking to say the least.
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I've actually seen that several times
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Woot... the Hill Country is my playground.
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I've actually seen that several times
Cool. Now u can tell people u have shot the guy down that designed that. :D
Yeah, Shuffler, that hill country lore is what I fancy, where streams run clear and Lord the skies they are so blue...
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well when i need calc's done on a home design i'll know where to throw my money lol
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Woot... the Hill Country is my playground.
(http://sphotos.ak.fbcdn.net/hphotos-ak-snc4/hs785.snc4/66567_1434373299828_1247804014_30976511_880782_n.jpg)
Thats over highway 46 at 7,200 feet.
(http://sphotos.ak.fbcdn.net/hphotos-ak-snc4/hs254.snc4/40044_1357783065120_1247804014_30817529_5538674_n.jpg)
San Antonio
(http://sphotos.ak.fbcdn.net/hphotos-ak-snc4/hs1216.snc4/156883_1485388535177_1247804014_31069274_7052098_n.jpg)
Lake Medina
Hey Sunbat, where in NB is that dome you built? Im sure ive seen it quite a few times, it looks pretty familiar
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Also Sunbat, did you know a guy named Gerhardt Kramer? (I think thats how you spell his name) He builds geodesic domes and was in new braunfels building one.
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Cool pics Tupac.
Makes me want to drag my 32 footer up there for a little camping and kayaking on the Guadalupe. :D
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Hey Sunbat, where in NB is that dome you built? Im sure ive seen it quite a few times, it looks pretty familiar
That dome is in Hunter, Texas which is pretty much right in between NB and San Marcos. You can see it from I-35.
That name sounds familiar, he may have been one of the construction hands that we hired on contract to work on that job. Can't remember for sure. :headscratch:
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if only the game had been going on - tons of snow. weeeeee
its mother nature's way of saying "You can't hide from me. Play like real men!"
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:rofl :rofl :rofl
First of all, all I said was "engineering fail". That is such a broad based comment I don't know why you are epically ranting over this. I could have meant the engineering of the fabric, or the engineering of the heating system, or the engineering of the roof. I honestly have not even looked into it at all other than this thread and the general news articles. I'm sorry for inferring that the structural engineer might have been to blame. Are you a structural engineer? I'm not, but I will be in about 3 years after I graduate with my M.S. in Structural Engineering, and finish up my work requirements to get licensed in my state. Anytime you want to talk loads, codes, dynamics, structural reliability, concrete design, steel design, masonry design, wood design, seismic design, etc. Let me know. :aok
We're looking for tensile strength here mate. :aok I'm not a licensed or formally edumacated civil and hydrolic engineer (I'm what you'll soon come to affectionatley reffer to as a CAD monkey (AACADD graduates), but I deal with the stuff 5-days a week and either the state OSHPOD or local/county Building and Safety inspectors and permits about once a week (and those overseeing department's codes and ordinances roughly only about 20 times an hour). Most of the standards you're learning in school are derived from the ordnances and codes that are overall the national standard, just a few things different here and there (IE: here in So Cal, you can throw out just about everything in school you'll learn about winterizing and distributing snowfall loads, but you'll be brushing up on and regularly frequenting topics on seismic safety, non-potable reclaimed water, rain-water retention systems, bio-filters for rain runoff, etc., etc.).
Make sure you take some project management cources while working on your degree in school, it'll really help you land a great position quicker out of school... otherwise there's a good chance you might be placed out of school as a subrodinate to some poor overworked and vindictive CAD monkey like me. :D
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Building code :)
:headscratch: whatabout it, I said it would/should of never been built in the first place if it didn't at least meet the minimum state and local codes and ordnances, baring a specific waiver issued by them for it. It's like a state-issued drivers permit, you have to meet the minimum requirements and get issued a permit, else it's illegal for you to ever drive and making you 100% liable for any accident or failure that occurs as a result - your fault or not. The state is only liable if they issued a permit to someone unfit or that fails to meet the requirements, or in this case if they issue a building permit for a set of plans that doesn't meet the codes and requirements the permit requires them to.
They engineer things that meet or exceed the specifications of the designer/owner(s) that then must comply to or exceed the state and local code and ordnance requirements (building codes). Assuming they didn't get away with constructing the roof of the Metrodome without a permit, and the construction of said roof met or exceeded the plans and specifications issued to the contractor, it's the fault of whoever at the state or local government level noded their head to the plans and put the stamp of aproval on it.
This is where my frustration kicks in, it's that people think this was as professionaly constructed as your neighbor's backyard shed, and that since the roof colapsed then it must be the fault of the nupty who engineered and built it. I spend a great deal of my profesional time having to "demonstrate, without any reason of doubt, to the state/local ____ inspector/permit-issuer, that everything within the scope of work being proposed meets or exceeds all requirements"... my usual frustrations kick in where state and local beurocracies meet the "without and reason of doubt" line (IE: a datum table displayed verticaly is denied for resubmital just because the inspector wants it in a horizontal format... stupid stuff like this happens often, and despite complaints they are in their full right to).
Something here went very wrong, and likely not at the level of the engineer who, unless there was some taboo under-the-table nagotions going on with the inspectors and the engineers/designers, likely met or exceeded what was specified to him.
As I said before, I'm guessing this was a failure of maintenance or operational procedure.
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Wrong. Any structural engineer that designs to the customer’s specifications and neglects the governing codes will not be an engineer very long. It is the responsibility of the engineer to protect the public even if that means the customer has to cancel the project because they are not willing to cover the cost. I don’t know all of the details related to this case so I will withhold my opinion, but I will say that the roof should have been designed according to the local and state building codes which would allow for a snowfall like that roof just experienced. If the engineer didn’t do that, they are very fortunate nobody was hurt and they deserve the lawsuit that is heading their way.
SunBat, P.E.
There is no way an under-engineered roof of the frakin Metrodome would of gotten constructed without at least a couple building permits issued from the state. If the roof did not meet those requirement but was issued a permit (aka: permission) then it is the state's fault, or rather, not the fault of the structural engineer, as the state said it was OK and fit the bill and standards.
I don't personaly know of a structural engineer that would of touched this idea with a 100-foot ductile iron pole, but owner-representing value engineers are another matter.
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Also Sunbat, did you know a guy named Gerhardt Kramer? (I think thats how you spell his name) He builds geodesic domes and was in new braunfels building one.
You reffering to the same Gerhardt Karmmer at Langdon Willson here in LA?
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Well the three PE's I talked to in the last couple of days all said the same thing. 'I'm glad my stamp wasn't on it'. The poo is going to fly far and fast and it will stick to as many people as it can.
And Bab.. CA building codes are so whack that I cringe every single time one comes across my desk.
When the big one hits the light poles will be the last things to go ;)
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There is no way an under-engineered roof of the frakin Metrodome would of gotten constructed without at least a couple building permits issued from the state. If the roof did not meet those requirement but was issued a permit (aka: permission) then it is the state's fault, or rather, not the fault of the structural engineer, as the state said it was OK and fit the bill and standards.
I don't personaly know of a structural engineer that would of touched this idea with a 100-foot ductile iron pole, but owner-representing value engineers are another matter.
Bingo, i design homes and some commercial buildings at times , the plans will not be passed without certified engineered spec's that must meet or exceed ALL State, County, and City structural codes, once passed it's Safe for the Public to occupy, and with that Roof System i'm sure they kept a good eye on it's construction, now you get into the did all the materials used in construction meets the Spec's ? , they must have or they never would of passed all the inspections during its construction OR did something happen with the climate control system that prevented it from supplying enough warmth into the Roof to keep the snow from accumulating on the Roof, there's going to be alot of finger pointing until this is all said and done
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Zoom are you a Civil or a PE?
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We're looking for tensile strength here mate. :aok I'm not a licensed or formally edumacated civil and hydrolic engineer (I'm what you'll soon come to affectionatley reffer to as a CAD monkey (AACADD graduates), but I deal with the stuff 5-days a week and either the state OSHPOD or local/county Building and Safety inspectors and permits about once a week (and those overseeing department's codes and ordinances roughly only about 20 times an hour). Most of the standards you're learning in school are derived from the ordnances and codes that are overall the national standard, just a few things different here and there (IE: here in So Cal, you can throw out just about everything in school you'll learn about winterizing and distributing snowfall loads, but you'll be brushing up on and regularly frequenting topics on seismic safety, non-potable reclaimed water, rain-water retention systems, bio-filters for rain runoff, etc., etc.).
Make sure you take some project management cources while working on your degree in school, it'll really help you land a great position quicker out of school... otherwise there's a good chance you might be placed out of school as a subrodinate to some poor overworked and vindictive CAD monkey like me. :D
Hah, well thx, I have an engineering position at a consulting office too, I'm not just going to school. :)
Thx for the tip on tensile strength, I'll look that one up, never heard of it before. Hopefully I can also learn how to draw a shear and moment diagram while I'm at it. :angel:
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I love it when CADD monkeys try to talk engineering. It's cute.
SunBat, P.E.
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Here's more things to nibble on: "Maki said he had about seven workers on the roof Saturday, blasting hot water with fire hoses to get rid of the snow."
http://www.startribune.com/sports/vikings/111730439.html?elr=KArksi8cyaiU9PmP:QiUiD3aPc:_Yyc:aUjEkD_hEK_kchO7DU (http://www.startribune.com/sports/vikings/111730439.html?elr=KArksi8cyaiU9PmP:QiUiD3aPc:_Yyc:aUjEkD_hEK_kchO7DU)
Ice + some of the wettest snow I've seen in 37 years. Again, the roof was screwed from the get go in this storm. Maybe they'll remove the dome and use it as an open air stadium.
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Zoom are you a Civil or a PE?
if your refereeing to an engineer, no i still would have a couple years left for that degree, I've been mulling that over ever sense the housing market took a dump, but 2 years structural design, then 2 years working with Bill Clemens Jr a former Oregon State Building Offical been in Structural engineering for the past 30 years, when the WTC went down he was part of the investigation team that studied what was left, anyway under him i would do all the drawings of the homes and commercial buildings into final form and Bill would do the engineering, run the calc's , sheer loads, beam sizing, ect, all the good stuff them guys get paid the big bucks for :) i should go back and finish, liked designing structures :aok
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I've thought about it Zoom as I pretty much 'get' all of the codes I have to deal with. Been dealing with them off and on for 15 years. If you've only got two to go you should imo. My industry could use more people with common sense.
Hmmmm.. this is getting interesting.
Okay pop quiz for all of the enginerds out there.
You have a supporting structure originally designed with an embed depth of 10 ft of 65 ksi steel (galvanized and mastic coated ((industry standard depth and protection)). The PE of record recommends, due to soil conditions, a drilled caisson of 12' depth 18" OD to 6" above ground level. The contractor calls and wants to backfill with #7 rock and soil instead of pouring the caisson or cold jointing it so, in the future, he can get to his below grade wiring.
What's your answer?
I'll reserve mine because I already know it.
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yea i should go finish it out, I've been in the construction field for about 26 years, last 17 was heavy equipment operator , doing all phases of earthwork, residential, commercial, logging road construction, safeways, freddie's list goes on when i had my injury in 2000 that's when i was told heavy construction carrer was over and i had to look for something else, took almost 4 years of rehab and pain management classes, injections only to end up with a class 2 permanate disabilty of the lower back, so i went into home/structural design sense i knew almost all the phases of construction industry, i love drawing peoples dreams into reality
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Based on latest code it probably should have been designed, assuming a cold roof, for 24psf flat snow load, 5psf rain on snow, round it up to 30psf...(not sure about the code 30 years ago)
30psf load with 20.5pcf density
30/20.5 = 1.46ft = 17.6 inches snow design. Assuming no unbalanced snow, (and proper drainage) which I don't know enough about a dome structure to know if you can make that assumption. So hell, after all safety factors, are taken into account from both snow loads and fabric loads I would think it would be able to take at least 40psf of load before failing, which would be 2 feet of snow. Not enough info though.
Did anyone check the snow fall that day,2 feet fell in many places,in fact in some place 3 to 5 feet fell.
I think Grizz is about spot on because I saw a snow fall of 60 cm,for that area,which is 24 to 25 inches.
We had 160 cm total now since the day of the colapse,which exceeds the total for all of last winter and winter doesnt start for another 6 or 7 days.... 160 cm equals roughly 62 inches.
:salute
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I'm not seeing nearly as much excitment about it here in Minnesota as on the AH BBS. It's the Dome after all. This happened before and it's the Vikings. We expect something to go wrong!
The bigger drama right now is Minneapolis and St. Paul getting the roads cleared. The Burbs did fine, but the Mpls/St.Paul have not done a very good job at clearing the roads. As one who had to work that day, and couldn't just call in, I can tell you that driving was insane and I'm still sore from all the shoveling. Last time it was this bad was Holloween 91. I've got a picture of our car showing only the roof from that one :)
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You reffering to the same Gerhardt Karmmer at Langdon Willson here in LA?
I'm not sure
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Bingo, i design homes and some commercial buildings at times , the plans will not be passed without certified engineered spec's that must meet or exceed ALL State, County, and City structural codes, once passed it's Safe for the Public to occupy, and with that Roof System i'm sure they kept a good eye on it's construction, now you get into the did all the materials used in construction meets the Spec's ? , they must have or they never would of passed all the inspections during its construction OR did something happen with the climate control system that prevented it from supplying enough warmth into the Roof to keep the snow from accumulating on the Roof, there's going to be alot of finger pointing until this is all said and done
Agreed, I feel sorry for most the parties involved as they won't be at fault but will be a long and ugly ride during the investigation/liability-insurance/civil-attorney hash-n-$. It won't bode well for their reputations either, regardless of whatever is eventualy concluded.
Hah, well thx, I have an engineering position at a consulting office too, I'm not just going to school. :)
Thx for the tip on tensile strength, I'll look that one up, never heard of it before. Hopefully I can also learn how to draw a shear and moment diagram while I'm at it. :angel:
Good luck, a solid engineering firm (either as an employee or owner of the company) is worth its weight in gold to you, so I hope it works out well for ya. You're being sarcastic about tensile strength I hope :uhoh lol (Laymans term for tensile strength is how much something will bend/give before utterly failing/breaking/ripping).
I love it when CADD monkeys try to talk engineering. It's cute.
SunBat, P.E.
I love when engineers/architects undervalue those that carry them in the workplace. [Fresh 4year+ graduate] < [2year-min-expereince 2year-orless CADD certified/degreed 'monkey']. :devil
I'm not sure
I believe he's one of the principles at a huge firm here in LA, one of our good clients... when paying our invoices up to current... but anywho. My father and him have been friends in the buisness for many many years.
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Good luck, a solid engineering firm (either as an employee or owner of the company) is worth its weight in gold to you, so I hope it works out well for ya. You're being sarcastic about tensile strength I hope :uhoh lol (Laymans term for tensile strength is how much something will bend/give before utterly failing/breaking/ripping).
:lol
Of course I was being sarcastic. I have a bachelors in civil engineering, have taken and passed the fundamentals of engineering exam, am currently in grad school getting my master's in structural engineering, and also work at a consulting office. I think I know what "tensile capacity" is. :aok
Oh, and your definition is incorrect. Carry on though cad monkey. :D
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Obvious answer seems to me to be to just tear the damn thing off.
When they build a new stadium. If they still insist on having a roof on it. then follow some sort of Norse design. Unlke todays nimrods that call themselves architects/engineers. The norsemen knew how to build structures that made sense for the environment they were in. (read, they knew how to build buildings that shed the snow)
Im talking design. not necessarily the same materials used.
Although in some of these cases. the materials used are probably more structurally superior that that bit of fabric covering the dome
Norse mill
(http://mw2.google.com/mw-panoramio/photos/medium/19263670.jpg)
Building n a reconstructed Viking foortress
(http://www.corbisimages.com/Images/spacer.gif)
Viking Storage house
(http://static-p4.fotolia.com/jpg/00/07/69/33/400_F_7693362_AzAlO6XKmOctdX6ZspxicKCQ5Z7zC6IC.jpg)
(http://imagecache6.allposters.com/LRG/21/2189/AFFAD00Z.jpg)
Now. I ask you. Look at those photos above. And look at the Metrodome below.
Which would you trust more in a heavy snowstorm?
(http://www.worldstadiums.com/stadium_pictures/north_america/united_states/minnesota/minneapolis_metrodome1.jpg)
They didnt build em to look like this for a reason
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I used to think the PE registration process was absurd until I read this thread. Thank you for making my PE registration mean something Dred, et al. I was afraid I went to school, practiced engineering for all those years, and passed that impossible test for nothing. Please keep drafting for dollars and imagining that u know what ur talking about while the real engineers make sure the public is safe. Please.
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Obvious answer seems to me to be to just tear the damn thing off.
When they build a new stadium. If they still insist on having a roof on it. then follow some sort of Norse design. Unlke todays nimrods that call themselves architects/engineers. The norsemen knew how to build structures that made sense for the environment they were in. (read, they knew how to build buildings that shed the snow)
Im talking design. not necessarily the same materials used.
Although in some of these cases. the materials used are probably more structurally superior that that bit of fabric covering the dome
Norse mill
(http://mw2.google.com/mw-panoramio/photos/medium/19263670.jpg)
Building n a reconstructed Viking foortress
(http://www.corbisimages.com/Images/spacer.gif)
Viking Storage house
(http://static-p4.fotolia.com/jpg/00/07/69/33/400_F_7693362_AzAlO6XKmOctdX6ZspxicKCQ5Z7zC6IC.jpg)
(http://imagecache6.allposters.com/LRG/21/2189/AFFAD00Z.jpg)
Now. I ask you. Look at those photos above. And look at the Metrodome below.
Which would you trust more in a heavy snowstorm?
(http://www.worldstadiums.com/stadium_pictures/north_america/united_states/minnesota/minneapolis_metrodome1.jpg)
They didnt build em to look like this for a reason
It doesn't sound like you have a very good understanding on how the engineering world works. Just sayin.
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My Daughter was taking meteorology. The engineering students in her calc class were shocked to hear that she had to take much math than engineering required.
I would have never thought that before.
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My Daughter was taking meteorology. The engineering students in her calc class were shocked to hear that she had to take much math than engineering required.
I would have never thought that before.
Meteorology requires more math than engineering? :huh
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Doubtful.
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The Gerhardt I'm talking about has a young kid, he went to a school that my mom taught at.
He also has a very thick German accent
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I looked it up, more than I thought but still much less than engineering at my university. I didn't compare to that schools engineering program though.
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Meteorology requires more math than engineering? :huh
Much more.
She goes to Texas A&M. A school known for it's engineering. It is also one of the top 3 in the nation for Meteorology.
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In all honesty, ice and snow brought the roof down. Noone was injured, killedn etc.
But this thread has long passed reached the "Lasersailor Level" on the meter.
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Grats Shuff!
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In all honesty, ice and snow brought the roof down.
It's the engineer's job to make sure that doesn't happen.
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Much more.
She goes to Texas A&M. A school known for it's engineering. It is also one of the top 3 in the nation for Meteorology.
Broad generalities are misleading. What kind of engineering? What specialty in meteorology? These questions must be answered to know for sure. I can see meteorology requiring a good amount of math though. I think it would be a really cool field to get into.
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Until Mother Nature throws a curveball.
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Until Mother Nature throws a curveball.
I don't have the time to get into the specifics but the codes that specify the environmental loads and the material design codes are specifically written to address when mother nature throws a "curveball". Having said that, in every design there is always a small probability of failure and as long as the engineer has properly designed according to all applicable codes, then they have a chance of being exonerated. I would be willing to bet though that this was not the case with this failure for the main and simple reason that many others roofing structures would have failed in the area.
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When designing a building what codes do you use or are the most prevalent? Also how do you determine the amount of wind / ice / etc loading to consider in your design?
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Clearing a domed roof off with 7 fires in temperatures around 20 degrees with heavy snowfall is asinine. This was obviously "recommended care" passed along to the site of the HHH Metrodome.
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When designing a building what codes do you use or are the most prevalent? Also how do you determine the amount of wind / ice / etc loading to consider in your design?
The short answer is that most states and cities have their own building codes. However, most of these building codes refer to “the latest version” of ASCE-7 – “Minimum Design Loads for Buildings and Other Structures” for the derivation of environmental loadings such as wind, snow and seismic. The various materials of construction such as Steel, Concrete, Wood, Aluminum, Masonry, etc, etc each have their own codes that provide methods to determine strengths of the various structural components that compose the structure. The engineer has to analyze the structure under the imposed loads to determine the stresses in the structure and then make sure that each component meets the material code requirements.
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Clearing a domed roof off with 7 fires in temperatures around 20 degrees with heavy snowfall is asinine. This was obviously "recommended care" passed along to the site of the HHH Metrodome.
If the owners agreed to maintain the roof in that way, they should have done it or had the roof modified to accomodate their maintenance requirements - of course that would have cost money because they would need to hire engineers to revise the design and then pay to have the modifications installed. Instead they probably had someone like Dred advise them that the engineers were "uptight and incompetent and the entire structure is way over designed" and since they were accountants and business men, they were way smarter than the engineers and they agreed with Dred that the engineers were idiots - right up until the moment the roof fell down. Now it's really going to be expensive. :D
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Thanks
As I said previously, I do find discussions of structural engineering and techniques fascinating. There's none of it, in my opinion, that isn't worth having at least a passing knowledge about.
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When designing a building what codes do you use or are the most prevalent? Also how do you determine the amount of wind / ice / etc loading to consider in your design?
Clearing a domed roof off with 7 fires in temperatures around 20 degrees with heavy snowfall is asinine. This was obviously "recommended care" passed along to the site of the HHH Metrodome.
ASCE Chapter 7 gives design procedure and values for snow loads based on U.S. location.
Where do these values come from? This is a complex issue and you creep into the concept of Structural reliability/probability. The core concept of reliability is minimizing the probability of failure while maximizing safety. The more "safe" you make a structure the more costly it becomes and economically unfeasible. The acceptable level of safety in structural components such as the metrodome is probably in the realm of Beta Value between 3.5-4.0 This is basically just a statistical Z value. Such values would give a PF between .000233 & .0000317. You basically back calculate what your design loads need to be based on the statistical probabilities. Snow fall can be idealized as an Extreme Type 1 Gumbel Distribution: http://www.itl.nist.gov/div898/handbook/eda/section3/eda366g.htm
Based on what your load resistance model is, you can do testing to see what kind of distribution it will also have. Then you run Monte Carlo Simulations, ala, hundreds of thousands of runs with random variables to see what the probability of failure is, and then back calculate your design snow loads to make sure this probability of failure is an acceptable value.
So yes, engineering is a science and these design values have incredible merit. As long as everything is designed, constructed, and maintained as design specifies, then the probability of failure should be slim to none and would require a "perfect storm" of events to take place for it to fail. A perfect storm combination would include: A slight human error in calculations, a very large load, a slightly damage component. Or something to that effect. Or, the storm of the century. Was this the most epic storm Minneapolis has ever seen? Did it set some century old record? Not that I'm aware of.
(http://i379.photobucket.com/albums/oo237/grizz441/snow.png)
Ground snow values for United States.
Desisn is based on 50 year extreme's.
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Thanks Grizz.
Do you consider a reduced wind based on snow / ice accumulation?
I just checked Minneapolis in the ANSI/TIA/EIA-222-G and it's showing a 90 mph maximum wind.
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Thanks Grizz.
Do you consider a reduced wind based on snow / ice accumulation?
I just checked Minneapolis in the ANSI/TIA/EIA-222-G and it's showing a 90 mph maximum wind.
Yes minneapolis has a design wind of 90mph.
Sort of, that's where load combinations come into play. For all practical purpose, while there may be some correlation with the storm of the century, the max wind load will not occur at the same time the max snow load occurs, and also at that same time, an earthquake hits minneapolis. :D
These would be the appropriate LRFD load combinations if Wind and Snow were both acting on a component:
Take the worst case of these:
3. 1.2D + 1.6(Lr or S or R) + (L or 0.8W)
4. 1.2D + 1.6W + L + 0.5(Lr or S or R)
ASD would be:
D + H + F + 0.75(W or 0.7E) + 0.75L
+ 0.75(Lr or S or R)
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Much more.
She goes to Texas A&M. A school known for it's engineering. It is also one of the top 3 in the nation for Meteorology.
I don't doubt it requires a lot of math but idk about that. I have taken calc1-3,diff eq, matrix theory, statics&dynamics courses, structural analysis, structural statistics... Only math class I haven't taken is numerical methods.
I'm pretty sure all of those, aside from matrix theory are required.
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Thanks again Grizz. I probably won't ever be a full blown engineer but I can be somewhat useful if my knowledge base is broadened :aok
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I did not delve into it. I am going on what their Calc professor told them all in class.
When told what she had to take the engineering students were very surprised.
I'm figuring like anything else. You learn it the hard way in school then when in the job arena you have computers do most of the calcs. You must be able to understand what is being done though.
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You hit the nail on the head for me Shuffler. I got roped into running a program that designs structures 4 years or so ago. Fortunately I've had the guidance of a PE I've worked with for almost 15 years and he's helped a LOT. As I'll never actually be a full blown structural engineer I try to learn as much as I possibly can about it. Not only in my area but as many other areas as I can. Which is why I'm bugging Grizz and Sunbat as much as I can (sorry guys).
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You hit the nail on the head for me Shuffler. I got roped into running a program that designs structures 4 years or so ago. Fortunately I've had the guidance of a PE I've worked with for almost 15 years and he's helped a LOT. As I'll never actually be a full blown structural engineer I try to learn as much as I possibly can about it. Not only in my area but as many other areas as I can. Which is why I'm bugging Grizz and Sunbat as much as I can (sorry guys).
correct, Sunbat and grizz since Sunbat has been a licensed structural engineer for a while now. I'm just a wee old EIT working to become licensed in the future.
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I'm figuring like anything else. You learn it the hard way in school then when in the job arena you have computers do most of the calcs. You must be able to understand what is being done though.
You have computers do a lot of the hard calcs, but you have to know how to model. It's not as simple as just magically creating a structural model and then clicking a button that gives you the answers. It is difficult stuff and you have to know what you are doing to make sure that you make the correct estimates and boundary conditions.
I'd say I do about 60% of my calculations by hand though, especially when sizing individual members. When you look at more complex systems of multiple members acting together, computers become necessary.
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You hit the nail on the head for me Shuffler. I got roped into running a program that designs structures 4 years or so ago. Fortunately I've had the guidance of a PE I've worked with for almost 15 years and he's helped a LOT. As I'll never actually be a full blown structural engineer I try to learn as much as I possibly can about it. Not only in my area but as many other areas as I can. Which is why I'm bugging Grizz and Sunbat as much as I can (sorry guys).
I felt a little bad about making that statement to Babalonian about “CADD monkeys” because there are many many designers that I greatly respect. I actually don’t like that term (I had to rib him some though :D). As a matter of fact, the very guy that got me into Aces High was one of the best designers that I have ever worked with. He used to be on the boards a lot, his name was Yknurd and his in game name was Drunky. He was a designer much like the way you seem to be, he was always interested in learning and would have been a fantastic engineer but his circumstances in life never allowed him to make it to college and get a degree. He is smart as a whip, truly gifted with a tremendous capacity for spatial reasoning, has intense focus, and has that proverbial “snap” that is so cherished in our line of work. I have had the privilege of working with others like him and I am absolutely convinced, and nobody will ever be able to persuade me otherwise, that an engineer’s number one most valued asset is a good designer. You sound like that type of person, so keep up the good work.
And don’t let Grizz fool ya, one day he will make twice the enginerd that I am.
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Thank you SunBat.. :salute I remember Yknurd any idea how he is?
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<snip>
Oh, and your definition is incorrect. Carry on though cad monkey. :D
No... no, I think I'm correct.
I vote that we get Skuzzy in here to weigh on the final and absolute decision. :devil
The Gerhardt I'm talking about has a young kid, he went to a school that my mom taught at.
He also has a very thick German accent
Probabley not him, he doesn't have an accent at all... though, it might not be noticable given the super-thickness of the accents of some of the middle-eastern guys/gals working there.
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I felt a little bad about making that statement to Babalonian about “CADD monkeys” because there are many many designers that I greatly respect. I actually don’t like that term (I had to rib him some though :D). As a matter of fact, the very guy that got me into Aces High was one of the best designers that I have ever worked with. He used to be on the boards a lot, his name was Yknurd and his in game name was Drunky. He was a designer much like the way you seem to be, he was always interested in learning and would have been a fantastic engineer but his circumstances in life never allowed him to make it to college and get a degree. He is smart as a whip, truly gifted with a tremendous capacity for spatial reasoning, has intense focus, and has that proverbial “snap” that is so cherished in our line of work. I have had the privilege of working with others like him and I am absolutely convinced, and nobody will ever be able to persuade me otherwise, that an engineer’s number one most valued asset is a good designer. You sound like that type of person, so keep up the good work.
And don’t let Grizz fool ya, one day he will make twice the enginerd that I am.
Don't worry about it, every monkey has his day. :D I'll come up with something more witty nexy week, I'm preparing to take home some work I gotta hump over this weekend to meet a noon deadline on monday (that some 4-year degreed nupty inadvertently forgot to mention to me until last night, even though they knew about this deadline three weeks ago.... lesson for today kids; stay in school longer so you can enjoy your weekends, get paid twice as much, work half as hard, and deligate the overtime... am I mad? F-no, today is payday and tonight I PARTAY!).
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multiple members acting together
Is that your favorite part?
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Could the amount of wind moving snow on the metrodome roof have something to do with the collapse?
Some area barns where I live had the roof collapse. They were newer buildings. Besides the heavy snow load, there was so much wind that one side of a roof had very little snow and the other side would be stacked high with snow. Just to the south 16.6 inches of snow and about 30 miles north about 22 inches snow of where I live.
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Could the amount of wind moving snow on the metrodome roof have something to do with the collapse?
Some area barns where I live had the roof collapse. They were newer buildings. Besides the heavy snow load, there was so much wind that one side of a roof had very little snow and the other side would be stacked high with snow. Just to the south 16.6 inches of snow and about 30 miles north about 22 inches snow of where I live.
Windward or Leeward drifting (worst case) is to be superimposed on balanced snow load if an obstruction like a high wall or parapet exists. There are provisions for that, I'm not sure how that relates to a dome structure, but the engineers who designed it should have found out.
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I used to think the PE registration process was absurd until I read this thread. Thank you for making my PE registration mean something Dred, et al. I was afraid I went to school, practiced engineering for all those years, and passed that impossible test for nothing. Please keep drafting for dollars and imagining that u know what ur talking about while the real engineers make sure the public is safe. Please.
It doesn't sound like you have a very good understanding on how the engineering world works. Just sayin.
Ok. Rather then put up the text that immediately came to mind.
Explain to me my errors.
Im not an engineer thats true And true I dont have a full understanding of engineering. But I do get to be in the maintenance end of the work and can see what seems to be to be common sense reasoning.
Given the typical environment of the area. The dome was doomed to fail. Fortunately the failure wasnt worse and nobody was in the way, or on top when it did. which could have very easily happend considering that just hours earlier people were up there trying to clear it. You cant just let that much snow sit on top of something like that Let alone wet snow. Eventually something is going to give. You dont need to have an engineering degree to figure some things out
I bet if you had interviewed some of the maintenance workers even months ago. they would have predicted this to happen at some point.
You see. engineers design it. But the workers have to deal with the finished product hands on day after day.
Suns. How many wakes and hospitals have you been to that were caused by your superior engineering skills?
How much time have you spent on the maintenance end of some of your designs?
Engineers are capable of great accomplishments and horrible disasters. Sometimes within the same projects
It becomes dangerous when you have engineers who seem to think they have a lock on safety
(http://www.library.ubc.ca/scieng/engineeringfailure/challenger.jpg)
(http://www.library.ubc.ca/scieng/engineeringfailure/kobe.gif)
(http://cache.boston.com/bonzai-fba/Globe_Photo/2006/09/09/1157824559_3215.jpg)
Sun. based on your comment. I'd have to say you are possibly one of those liabilities
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Windward or Leeward drifting (worst case) is to be superimposed on balanced snow load if an obstruction like a high wall or parapet exists. There are provisions for that, I'm not sure how that relates to a dome structure, but the engineers who designed it should have found out.
Dunno if you have read this already or not. but ti gives some eplanation as to how the dome was supposed to work
http://engineeringfailures.org/?p=391#more-391
and in this post not trying to sound like too much of a wisearse but
Again I am not an engineer. But anyone who has ever had to shovel slush can tell you there is a slight difference in weight between wet snow and what is often called "dry" snow.
A better example of what Im trying to say is after a storm with a very cold snow how much lighter the snow is to move then if you wait for it to start melting.
This is because of the amount of air trapped between the flakes. the water content can range from 3% in a very "dry" snow to 33% in wet snow to 100% for ice
Again. using common sense. they were melting the snow from underneath. then steaming it also from above adding even more water to an already wet and heavy situation. This on what was from what I have read an already very wet snow to begin with thus removing the air from the snow making it even heavier in a more concentrated area.
Now I know this is a much different structure. But on a house the last thing you want is for the the snow to melt in such great amount on your roof. Ideally you want your attic and roof to be the same temperature as the outside
Referring back to the pictures I used in my original post. It would seem to me a far better design to simply create a roof with such a pitch as would simply not allow great amounts of snow to accumulate up there to begin with.
Now. if I am wrong. explain why.
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Suns. How many wakes and hospitals have you been to that were caused by your superior engineering skills?
How much time have you spent on the maintenance end of some of your designs?
Engineers are capable of great accomplishments and horrible disasters. Sometimes within the same projects
It becomes dangerous when you have engineers who seem to think they have a lock on safety
(http://www.library.ubc.ca/scieng/engineeringfailure/challenger.jpg)
(http://www.library.ubc.ca/scieng/engineeringfailure/kobe.gif)
(http://cache.boston.com/bonzai-fba/Globe_Photo/2006/09/09/1157824559_3215.jpg)
Sun. based on your comment. I'd have to say you are possibly one of those liabilities
Um. None, thankfully. I also don’t remember making a statement that implies that I think I can never make a mistake. It’s a good thing for an engineer to make the person that he/she trusts the least be themselves.
There is no way for me to go into any detailed explanation of the intricacies of structural engineering. For me to do it any justice, I would have to impart to you the equivalent of at least four years of ABET accredited education and many years of practical engineering experience in addition to that.
I said earlier in the thread that I would withhold my opinion of this case because I know how intricate and detailed these things can be and it is impossible to know all of the factors involved just sitting at my computer and guessing. This is the major distinction between me and you. You made a post with “authority” about how it should be done, and I know there is way too much to be considered for me to pass judgment based on what I read over the internet.
That’s the problem with people like you. You think you know, and you make decisions and judgments based on what you think you know. I actually won’t say until I do know. Most good engineers won’t pass judgment until they have taken the time to sit down and analyze all of the factors involved in a design or situation. That drives maintenance people, project managers, plant operators, facility owners, construction hands, fabrication technicians and drafters crazy because they think they know better than the engineer. They don’t.
I can’t tell you how many times in my thirteen years of engineering experience I have caught a construction hand or a maintenance person modifying my design to such an extent that it really could kill someone. Thankfully I had the way to check on them and not leave them to their own devices where they were sure they were correct and I was the “idiot”. In most of the “engineering” failures that you hear about in the news, it is not the engineer that messed up but some slipshod construction outfit or maintenance person that decided to take a short cut when they were installing or maintaining the engineer’s design. I would be willing to bet that that was the case with a lot of those pictures that you posted.
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Dunno if you have read this already or not. but ti gives some eplanation as to how the dome was supposed to work
http://engineeringfailures.org/?p=391#more-391
and in this post not trying to sound like too much of a wisearse but
Again I am not an engineer. But anyone who has ever had to shovel slush can tell you there is a slight difference in weight between wet snow and what is often called "dry" snow.
A better example of what Im trying to say is after a storm with a very cold snow how much lighter the snow is to move then if you wait for it to start melting.
This is because of the amount of air trapped between the flakes. the water content can range from 3% in a very "dry" snow to 33% in wet snow to 100% for ice
This is already common knowledge and factored into design Dred. This isn't common sense stuff that the 'idiot engineers' didn't think of. Here is the design equation for the density of snow:
γ = 0.13pg + 14 but not more than 30 pcf
pg is the ground snow load, and is 50psf for Minneapolis. Do the math, and compare that number to the density of water and see what you come up with. It's not like this "wet snow" thing is something the "idiot engineers" didn't think of.
I can't even comment on the design of the dome, I haven't the slightest clue about it, or the designed drainage system, or its required maintenance schedule.
I'm curious though, what point are you trying to make? That structural engineers are over payed idiots?
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Dred,
As I believe I've posted before in this thread nobody will know for sure what the CAUSES of the incident were until the full report is filed.
Suffice it to say that, based on discussions with PE's that I know and respect, my own thoughts, and the thoughts of others, the ultimate cause of the incident is fairly obvious. The reason for that happening is not so obvious.
Oh and Sunbat... 'Project Designer' :) I like that title. I'm, seriously, going to ask my boss to put it on my business card underneath 'Project Manager', 'IT Director' (laughing is okay I do), and 'Sales Manager'. He balked at 'Head Number One Doo Doo Boy' :lol
Back to seriousness. When I drive past or see something I designed I tend to grin thinking back and saying 'who would have thought I'd be doing this 20 years ago'. My aim is to make damn sure that what I design is safe and standing until the owner decides to remove or replace it. I can recommend certain steps that the owner needs to do to maintain the structural integrity of the structure but I'm not in the position to demand it. If they dont.. well there might be averse consequences of their failure to heed my advice.
I can't and won't go any further in a public forum other than to say I trust the engineers I work with and know, if I miss something, they'll point it out to me and I can make corrections. Imagine what it would feel like knowing your seal was on something that failed catastrophically due to causes unknown. The engineer in question is guilty until proven innocent. Tends to make MOST of them careful. I know I am and I'm just a project designer ;)
For Sun and Grizz.. A couple I did that I'm kind of proud of.
(http://www.littleballparks.com/Stadium/2001/Rochester/Images/Rochester_01009.jpg)
(http://www.texasbob.com/stadium/simages/255.jpg)
The second one is interesting because it's an embedded pole in a 15 ft berm. Got a TON of schooling from my PE buds on that one. Wish I could find the construction pics of the first one.
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I can’t tell you how many times in my thirteen years of engineering experience I have caught a construction hand or a maintenance person modifying my design to such an extent that it really could kill someone. Thankfully I had the way to check on them and not leave them to their own devices where they were sure they were correct and I was the “idiot”. In most of the “engineering” failures that you hear about in the news, it is not the engineer that messed up but some slipshod construction outfit or maintenance person that decided to take a short cut when they were installing or maintaining the engineer’s design. I would be willing to bet that that was the case with a lot of those pictures that you posted.
There lies the whole problem, it's "trying to save a buck" that leads to Structural Failures, like you posted deviating from an Engineered plan to save a buck or cut a corner is not worth a human life, just glad that no one was hurt when the Roof did collapse, all this discussion has really perked my interest in finishing my last 2 years, but oh i hate all the Math :old:
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you hate it?
I add 2+2 and get 'chartreuse'. ;)
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lol yea still having them 70's flashbacks :rofl :rofl
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dang 'mind expanders'